From early prenatal development through childhood, the prefrontal cortex of the human brain undergoes an avalanche of developmental activity. In some cases, it also contains seeds of neuropsychiatric illnesses such as autism spectrum disorder and schizophrenia, according to a new genetic analysis.

Previous studies have identified DNA variants linked to neuropsychiatric illnesses, but it has been unclear just when those variations might trigger functional changes in the dorsal lateral prefrontal cortex, a region closely linked to neuropsychiatric, cognitive, and emotional disorders. This new study, published in the journal Cell Reports, added a new dimension to prior research. The scientists also measured the amount of RNA, which provides a picture of overall gene activity, in 176 tissue samples across a variety of developmental stages to determine how and when DNA variants influence brain function.

"This is the first large cohort to profile DNA and RNA both in prenatal and postnatal human brain samples, making it an unprecedented resource for understanding how individual genetic differences might lead to functional differences," said a co-lead author of the study.

The authors identify common variants that alter gene expression (expression quantitative trait loci [eQTLs]) constantly across development or predominantly during prenatal or postnatal stages. Both “constant” and “temporal-predominant” eQTLs are enriched for loci associated with neuropsychiatric traits and disorders and colocalize with specific variants. Expression levels of more than 12,000 genes rise or fall in a concerted late-fetal transition, with the transitional genes enriched for cell-type-specific genes and neuropsychiatric risk loci, underscoring the importance of cataloging developmental trajectories in understanding cortical physiology and pathology.

Understanding how genetic variation and changes in function are linked will help scientists understand how alterations of brain development can lead to schizophrenia and autism later in life, said the authors of the study. Since the research tracked thousands of variants associated with thousands of genes across the entire genome, scientists can identify groups of genes that regulate distinct biological processes and study how they can lead to disease, they said.

"Human brain development is an incredibly complex and dynamic process, and any disruption along the way can have profound consequences on later brain function," said the other co-lead author. "Interestingly, we found that some genetic variants have stronger effects on RNA expression before birth and other variants with strongest effects after birth."

Studying these age-specific effects can open more doors for learning about the mechanisms behind brain disorders, the authors said.

https://news.yale.edu/2020/04/07/genes-sow-seeds-neuropsychiatric-diseases-even-birth

https://www.cell.com/cell-reports/fulltext/S2211-1247(20)30367-3

http://sciencemission.com/site/index.php?page=news&type=view&id=publications%2Fwhole-genome-and-rna&filter=22